1. Field of the Invention
The present invention relates to a thin film magnetic head provided with an induction type magnetic recording head and a method of manufacturing the same.
2. Description of the Related Art
A composite type thin film magnetic head including a magnetoresistive (MR) head used for data reproduction and an induction type magnetic head used for data recording is used as a magnetic head of a magnetic disk device.
The MR head includes any one of an AMR (Anisotropic Magnetoresistive) component using an AMR effect, a GMR (Giant Magnetoresistive) component using a GMR effect, and a TMR (Tunneling Magnetoresistive) component using a tunnel junction film indicating a magnetoresistive effect. As the surface recording density of a magnetic recording medium becomes high, a component to be used is changed from the AMR component to the GMR component, and further, to the TMR component.
As one factor for determining the performance of the MR head, there is optimization of an MR height. The MR height is a height of the MR component from an end portion at a side facing an air bearing surface (ABS) opposite to a magnetic recording surface of a magnetic recording medium to an end portion at the opposite side, and this height depends on an amount of polishing of the ABS surface in a head manufacturing process.
The induction type magnetic head realizes a ring structure having a narrow gap by a semiconductor process, and includes upper and lower magnetic pole layers which are laminated through an insulating film and has a gap (write gap) at the side facing the ABS surface to form a closed magnetic path, and a thin film coil formed in the insulating film between upper and lower magnetic poles. The head material is magnetized to have high magnetic flux density by a recording current flowing through the thin film coil, and a predetermined leakage magnetic field is formed over the gap to record data.
As one factor for determining the performance of the induction type magnetic head, there is optimization of a throat height (TH). The throat height is a height of the magnetic pole from the ABS surface to the end portion of the insulating film, and this height also depends on an amount of polishing of the ABS surface in the head manufacturing process. In order to improve the head efficiency of the recording head, it is necessary to make the throat height as short as possible.
In order to raise the recording density, it is necessary to raise the track density of the magnetic recording medium. For that purpose, it is necessary to realize a recording head in which a magnetic pole width and a gap width at the ABS surface are made narrow; therefore a semiconductor processing technique is used.
The foregoing composite type thin film magnetic head is manufactured through a plurality of manufacturing processes, for example, a sputtering process, a photolithography process, a frame plating process, an etching process, a polishing process, and the like. Hereinafter, an example of a method of manufacturing a thin film magnetic head will be described in brief by use of the thin film magnetic head having a so-called step gap structure.
First, an Al2O3TiC substrate having high hardness and excellent in wear resistance is used. When the magnetic head is completed, this substrate itself functions as a slider body of the magnetic head. The reason why the substrate having high hardness and excellent in wear resistance is used is to secure the floating accuracy of the head and to obtain an accurate MR height and throat height.
Then, for example, a chromium film excellent in adhesiveness is formed on the Al2O3TiC substrate by sputtering or the like. Next, a lower shield layer made of, for example, permalloy is formed. Next, an MR component interposed between insulating films is formed on the lower shield layer.
Next, an upper shield layer made of, for example, permalloy is formed. By this, an MR head for reproduction is completed. The upper shield layer is also used as a lower magnetic pole layer of an induction type magnetic head for recording. Next, a thin film coil made of copper or the like is formed on the lower magnetic pole layer through an insulating film by a frame plating method or the like.
Next, after the thin film coil is embedded in an insulating film and flattening is made, a recording gap layer is formed on an upper layer. A process from the formation of the recording gap layer to the formation of an upper magnetic pole layer will be described in brief with reference to FIGS. 9A to 9F and FIGS. 10A to 10F. In FIGS. 9A to 9F and FIGS. 10A to 10F, FIGS. 9A, 9C and 9E and FIGS. 10A, 10C and 10E show sections vertical to the ABS surface, and show the sections taken along line Axe2x80x94A shown in FIG. 9B. FIGS. 9B, 9D and 9F and FIGS. 10B, 10D and 10F show partial planes near the ABS surface.
First, as shown in FIGS. 9A and 9B, a stepped portion (step gap) 158 of a nonmagnetic material with an almost vertical end face 159 at a side facing the ABS surface (see FIG. 10F) is formed on a recording gap layer 112.
Next, as shown in FIGS. 9C and 9D, after a seed layer 151 for a plating treatment is formed, as shown in FIGS. 9E and 9F, a positive resist 152 is coated on the entire surface and patterning is made to form a resist frame 153 (see FIGS. 10A and 10B).
Next, as shown in FIGS. 10C and 10D, a plating film made of, for example, permalloy is formed by a frame plating method using the formed resist frame 153 as a mold, and then, the resist frame 153 is removed and an upper magnetic pole layer 113 is formed (see FIGS. 10E and 10F).
Although not shown below, etching is carried out using the upper magnetic pole layer 113 at the side facing the ABS surface as a mask, so that the recording gap layer is patterned. The upper magnetic pole layer is formed so as to be magnetically connected to the lower magnetic pole layer through the coil at the opposite side of the recording gap layer so that a closed magnetic path is formed. A protection film is formed on the upper layer of the upper magnetic pole layer, and the film forming process is ended.
Next, the Al2O3TiC substrate is cut into rod-like substrates including several tens of heads. The ABS formation surface of the rod-like substrate is polished to provide the throat height of a height of several xcexcm. After the ABS surface is formed, the rod-like substrate is cut, so that a plurality of thin film magnetic heads are completed.
Like this, in the thin film magnetic head of the step gap structure, for example, as shown in FIGS. 10E and 10F, the stepped portion 158 of the nonmagnetic material in which the end face 159 at the side facing the ABS surface is formed almost vertically, is formed on the recording gap layer 112. By making the step gap structure, the upper magnetic pole layer 113 can be formed on the flattest possible surface.
Besides, according to the step gap structure, the throat height is defined as a height from the ABS surface to the end face 159 of the stepped portion 158. Here, the position of the end face 159 of the stepped portion 158 becomes a throat height zero (TH0) position. Thus, an interval between the not-shown lower magnetic pole layer and the upper magnetic pole layer 113 is a constant interval equal to the thickness of the recording gap layer 112 from the ABS surface to the throat height zero position, and abruptly becomes large from the throat height zero position (that is, the position of the end face 159) at the opposite side to the ABS surface.
However, like this, in the structure where the interval between the lower magnetic pole layer and the upper magnetic pole layer is abruptly changed in the vicinity of the throat height zero position, the flow of a magnetic flux passing through the magnetic pole layer and directed toward the recording gap layer is abruptly changed in the vicinity of the throat height zero position. Thus, there occurs a problem that the magnetic flux is saturated in the vicinity of the throat height zero position, and the electromagnetic conversion characteristics of the thin film magnetic head are deteriorated. The electromagnetic conversion characteristics are specifically overwrite characteristics in the case where data is overwritten in a region in which data is already written on a recording medium, non-linear transition shift (NLTS), and the like.
An object of the present invention is to provide a thin film magnetic head which can improve electromagnetic conversion characteristics, and a method of manufacturing the same.
The above object is achieved by a thin film magnetic head comprising a lower magnetic pole layer having one magnetic pole at a side facing an ABS surface, a gap layer formed on at least the one magnetic pole, a stepped portion of a nonmagnetic material formed on the gap layer and having an almost vertically formed end face at a side facing the ABS surface, a space portion formed at the end face, an upper magnetic pole layer including an other magnetic pole opposite to the one magnetic pole through the gap layer, formed on at least the gap layer, the space portion, and the stepped portion, and magnetically connected to the lower magnetic pole layer to constitute a closed magnetic path, and a thin film coil provided between the upper and lower magnetic pole layers through an insulating layer.
In the thin film magnetic head of the present invention, a throat height is defined by an end portion of the space portion at a side facing the ABS surface. Besides, the end portion of the space portion at the side facing the ABS surface is positioned closer to the ABS surface than an end portion of the other magnetic pole at an opposite side to the ABS surface. Besides, in the thin film magnetic head of the present invention, a side of the upper magnetic pole layer facing the space portion includes an inclined surface connecting a surface of the gap layer and the stepped portion.
Besides, the above object is achieved by a method of manufacturing a thin film magnetic head, the method comprising a step of forming a lower magnetic pole layer having one magnetic pole at a side facing an ABS surface on a substrate, a step of forming a gap layer on the lower magnetic pole layer, a step of forming, on the gap layer, a stepped portion of a nonmagnetic material having an almost vertical end face at a side facing the ABS surface, a step of forming a seed layer for a plating treatment, a step of carrying out patterning by coating a positive resist on an entire surface and exposing the resist by such an exposing amount as to leave the resist at the end face, a step of forming an upper magnetic pole layer including an other magnetic pole opposite to the one magnetic pole through the gap layer and magnetically connected to the lower magnetic pole layer to constitute a closed magnetic path, by a plating treatment using a resist pattern as a mask in which the resist is left at the end face, a step of forming a space portion with the upper magnetic pole layer, the gap layer, and the end face by removing the resist pattern and the seed layer of its under layer, and a step of forming a thin film coil between the upper and lower magnetic pole layers through an insulating layer.